This invention relates to an exposure time control device for use in an electric camera shutter. The device is of digital memory reproduction type, wherein the pulses developed from a pulse generating circuit are counted in a counter circuit which counts a number of pulses corresponding to the brightness of the subject to be photographed for thereby controlling the exposure time.
One technique for introducing exposure determining factors other than the brightness of the subject (for example, film sensitivity and diaphragm value) into an exposure time control device of aforementioned type has been proposed already in the U.S. Pat. No. 3,876,876 filed by the applicants of the present invention. According to the already proposed technique, in order to introduce exposure time determining factors other than the brightness of the subject to be photographed, the input position of reference pulses into a counter circuit is selected by a selector switch thereby permitting the introduction of factors such as film sensitivities and diaphragm values which are included in multiple series, but such a technique is disadvantageous in that it does not permit the introduction of film sensitivities outside of the multiple series such as ASA 125, ASA 160, ASA 250, ASA 320, etc.
It is therefore an object of this invention to eliminate the aforementioned disadvantage and to provide an improved exposure time control device for use in an electric camera shutter.